We are testing hypotheses about the synaptic organization of the stomatogastric nervous system of crustaceans, and the meaning of this organization for the production of motor patterns. These hypotheses are based on an extensive description of this organization. We have developed new methods to measure the electrotonic structure of neurons, and are now using these methods to describe quantitatively the integrative properties of the neurons in the stomatogastric system. These measurements are essential for the calibration of a digital simulation of the stomatogastric network that tests our hypotheses about the significance of the networks organization. We are also studying the sensory modulation of these motor patterns, and the physiology of synapses made by sensory interneurons with neurons of the stomatogastric system. We are investigating the physiology of graded synaptic transmission between two neurons of the stomatogastric system to see if there are unique consequences of graded transmission for the production of motor patterns.